1. Field of the Invention
This invention relates to hypodermic needle safety shields or enclosures, more particularly, a shield or enclosure that will receive a hypodermic needle cannula after use to safely enclose the cannula for disposal and prevent accidental puncture wounds.
2. Description of the Prior Art
Hypodermic needle cannula covers and safety shields have been known for some time. The interest in such devices has increased dramatically since the onset of AIDS and the recognition of the serious health problems associated with hepatitis. Both these illnesses are virus propagated. The virus can be readily transferred to a human through contaminated blood. A used hypodermic needle cannula contaiminated with AIDS or hepatitis infected blood can, by accidental puncture, cause the transfer of AIDS or hepatitis to a healthy or uninfected human.
U.S. Pat. No. 2,110,123 is directed to a hypodermic needle guard to prevent injury to the cannula tip during shipping, handling, sterilization, and the like. U.S. Pat. No. 2,997,043 discloses a protective sheath for a cannula which is used to protect the cannula prior to use. U.S. Pat. No. 3,537,452 discloses a needle cover and bevel guard which is designed to protect catheter tubes which are inserted into the body via a hypodermic needle cannula after removal of the cannula to prevent the cannula point from accidentally severing or puncturing the catheter tube. U.S. Pat. No. 4,643,722 discloses a guard for storage, transportation and disposal of hypodermic needles to prevent accidental puncture wounds following use of the needle. The guard is a tubular element having a longitudinal axial slot to permit entry of the cannula into the guard. To prevent exit of the needle from the guard, the guard is furnished with a removable sealing strip. U.S. Pat. No. 4,664,259 is directed to a hinged container enclosing a hypodermic needle cannula which is directly attached to the hub of a cannula. The container can be rotated away from the cannula with the cannula exiting through a slot in one wall of the container. In an alternative embodiment, the container has two wall segments hinged on opposite sides of the cannula which can be rotated away on their hinges to free the cannula for use. U.S. Pat. No. 4,747,836 discloses a cannula guard which is rotatably mounted at the base of the cannula and constitutes a half channel which receives the cannula. The cannula guard is rotated away from the cannula for use. The guard is rotated back to partially enclose the cannula after use and a cylinder is moved over the guard to enclose the cannula and the guard.
Although these cannula guards and enclosures are superior to the conventional cap-type enclosures which require that the used cannula point be centered into the open end of the cap and then projected into the cap during encapsulation. Medical workers, frequently during times of stress or fatigue, do not pay adequate attention to the cannula during the encapsulation process and accidentally puncture their hand or finger with the used cannula. Such accidental punctures have led to cases of hepatitis and AIDS, serious, life-threatening diseases.
The guard of U.S. Pat. No. 2,979,043 can only be used to protect a cannula before use. The metal guard of the U.S. Pat. No. 2,110,123 patent does not fully encapsulate the needle. The guard of the U.S. Pat. No. 3,537,452 patent is designed to be utilized with a catheter tube and, in the absence of a catheter tube, the cannula can exit via the elongated slot. The needle guard of the U.S. Pat. No. 4,643,722 patent has an open slot which, when not sealed, permits exit of the cannula. The slot can be fitted with a removable sealing strip, which can be used to cover the slot after entry of the cannula. However, a strip is inconvenient. The medical worker must place the sealing strip in a convenient location for retrieval after use of the cannula and must be careful when applying the sealing strip that the point of the cannula does not exit the slot and accidentally puncture the worker. In another embodiment, the sealing strip can be permanently attached to one end or side of the slot so that it is not separated from the guard. However, for this embodiment, the sealing strip must be held out away from the slot when the cannula is inserted into the guard. This can be a cumbersome process and, once again, expose the fingers or the hand to an accidental puncture wound. The needle container of the U.S. Pat. No. 4,664,259 patent is somewhat awkward and complicated and limits the area of access for the hypodermic needle because of the position of the open container. Similarly, the needle guard of the U.S. Pat. No. 4,747,836 patent is awkward to use because the needle guard is rotatably mounted to the base of the needle and can limit the area of access because of the physical incursion of the guard. The hypodermic needle guards of the U.S. Pat. Nos. 4,664,259 and 4,747,836 devices are relatively complex devices and much more costly than the hypodermic needle guards of the earlier patents.
The object of the present invention is to provide a needle guard which can easily receive the cannula of a hypodermic needle with minimum exposure to the user's fingers and hands to prevent accidental puncture wounds. In addition, it is an object of the present invention to provide a needle guard which encapsulates the cannula of a hypodermic needle to prevent or inhibit the exit of the cannula from the guard. Furthermore, it is an object of the present invention to provide a needle guard which can be manufactured from inexpensive materials, which comprises a relatively simple design which can be easily molded and which can be readily manufactured to provide a hypodermic needle guard at minimum cost.